A grim procession of climate science news

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Another day, another (accurate) apocalyptic review of climate science. Joining recent articles in the New York Times and New Scientist is a terrific piece in Scientific American by science writer John Carey.

Carey has collected an assortment of epic quotes and nightmare scenarios from leading climatologists. As he explains (behind a paywall):

The latest data from across the globe show that the planet is changing faster than expected. More sea ice around the Arctic Ocean is disappearing than had been forecast. Regions of permafrost across Alaska and Siberia are spewing out more methane, the potent greenhouse gas, than models had predicted. Ice shelves in West Antarctica are breaking up more quickly than once thought possible, and the glaciers they held back on adjacent land are sliding faster into the sea. Extreme weather events, such as floods and the heat wave that gripped much of the U.S. in the summer of 2012 are on the rise, too. The conclusion? “As scientists, we cannot say that if we stay below two degrees of warming everything will be fine,” says Stefan Rahmstorf, a professor of physics of the oceans at the University of Potsdam in Germany.

The X factors that may be pushing the earth into an era of rapid climate change are long-hypothesized feedback loops that may be starting to kick in. Less sea ice, for example, allows the sun to warm the ocean water more, which melts even more sea ice. Greater permafrost melting puts more CO2 and methane into the atmosphere, which in turn causes further permafrost melting, and so on.

The potential for faster feedbacks has turned some scientists into vocal Cassandras.

Well, let’s hope faster feedbacks haven’t turned climatologists into Cassandras. That would mean we are doomed to be seduced by the Trojan horse of fossil fuels with the civilization-destroying carbon pollution hiding inside, to extend the metaphor (see “Will Sandy Be Short For Cassandra, Another Warning We Ignore?“).

This isn’t the only blunt climate article in Scientific American. They just published:

Climate Change Threatens to Create a Second Dust Bowl

Rising temperatures, persistent drought, and depleted aquifers on the southern Great Plains could set the stage for a disaster similar to the Dust Bowl of the 1930s, scientists say

Carey’s piece lays out one of the main reasons climate scientists are concerned about abrupt, catastrophic change driven by greenhouse gases — it has happened in the past:

Some changes in the past were incredibly rapid. Work on Red Sea sediments by [climatologist Eelco] Rohling shows that during the last warm period between ice ages—about 125,000 years ago—sea levels rose and fell by up to two meters within 100 years. “That’s ridiculously fast,” Rohling says. His analysis indicates that sea levels appear to have been more than six meters higher than they are today—in a climate much like our own….

Also surprising is how little extra energy, or “forcing,” was required to trigger past swings. For instance, 55 million years ago the Arctic was a subtropical paradise, with a balmy average temperature of 23 degrees C (73 degrees F) and crocodiles lurking off Greenland. The tropics may have been too hot for most life. This warm period, dubbed the Paleocene-Eocene Thermal Maximum (PETM), apparently was sparked by a preceding bump of about two degrees C in the planet’s temperature, which was already warmer than today. That warming may have caused a rapid release of methane and carbon dioxide, which led to more warming and more emissions of greenhouse gases, amplifying further warming. The eventual result: millions of years of a hothouse earth.

In the past 100 years humans have caused a warming blip of more than 0.8 degree C (1.4 degree F). And we are pouring greenhouse gases into the atmosphere 10 times faster than what occurred in the run-up to the PETM, giving the climate a mighty push…. “If we burn all the carbon we have access to, we’re pretty much guaranteed of having a PETM-like warming,” [earth and atmospheric scientist Matthew] Huber says.

But Huber — and I — would appear to be optimists compared to Euan Nisbet, a professor of earth sciences in London:

Nisbet’s own “nightmare scenario” starts with a blip in methane emissions and a very warm summer that leads to massive fires, pouring carbon into the atmosphere. The smoke and smog blanket Central Asia and weaken the monsoons, causing widespread crop failures in China and India. Meanwhile a large El Niño pattern of unusually warm water in the tropical Pacific brings drought to the Amazon and Indonesia. The tropical forests and peatlands also catch fire, injecting even more CO2 into the atmosphere and putting the climate on the fast track to rapid warming. “It’s a feasible scenario,” Nisbet observes. “We may be more fragile than we think we are.”